King Tutankhamun Posted April 7, 2004 Share Posted April 7, 2004 Wooooza! That is impressive Mark. Is that right Dnas? Link to comment Share on other sites More sharing options...
Dnas Posted April 7, 2004 Share Posted April 7, 2004 Yup. Link to comment Share on other sites More sharing options...
MarkT Posted April 8, 2004 Share Posted April 8, 2004 Solve simultaneously:3a + b - c =10,a - 2b + 3c = -7,2a + 3b - 2c = 15a = ?, b = ?, c = ?Bonus points for solving it via a matrix method. Link to comment Share on other sites More sharing options...
Mystic-Al-Bob Posted April 9, 2004 Share Posted April 9, 2004 a=2,b=23-10a=3c=13 -7a =-1 Link to comment Share on other sites More sharing options...
Jeru Posted April 9, 2004 Share Posted April 9, 2004 Got the same results.Never heard of the matrix method. Link to comment Share on other sites More sharing options...
Dnas Posted April 10, 2004 Share Posted April 10, 2004 The matrix method is putting it in reduced row echelon form. Search on Google for it or something. Link to comment Share on other sites More sharing options...
MarkT Posted April 11, 2004 Share Posted April 11, 2004 Yes, correct. Link to comment Share on other sites More sharing options...
Argalius Posted April 12, 2004 Share Posted April 12, 2004 The matrix methodIs that simple math?!?! Link to comment Share on other sites More sharing options...
MarkT Posted April 12, 2004 Share Posted April 12, 2004 The matrix methodIs that simple math?!?! Relatively speaking... Link to comment Share on other sites More sharing options...
av_nefardec Posted April 12, 2004 Share Posted April 12, 2004 Never heard of the matrix method. The matrix method is putting it in reduced row echelon form. Search on Google for it or something.Well to search it I'd tell you to look for Gauss-Jordan Elimination - that's the actual method used.But you could also invert the coefficient matrix and multply it by the matrix each equation equals.3a + b - c =10,a - 2b + 3c = -7,2a + 3b - 2c = 15[3 Â 1 Â -1]^-1 Â Â Â Â Â [10] Â Â Â Â Â Â Â Â Â Â [a][1 Â -2 Â 3] Â Â Â Â * Â Â [-7] Â Â Â Â = Â Â Â Â Â [b][2 Â 3 Â -2] Â Â Â Â Â Â Â [15] Â Â Â Â Â Â Â Â Â Â Â [c]This should give you the answers you need. The only problem is inverting the 3x3 matrix, which is usually a pain to do by hand.*waves his calculator about in the air* Link to comment Share on other sites More sharing options...
Argalius Posted April 13, 2004 Share Posted April 13, 2004 Really ... euhh ... interesting. Link to comment Share on other sites More sharing options...
Mystic-Al-Bob Posted April 15, 2004 Share Posted April 15, 2004 I still don't understand. Link to comment Share on other sites More sharing options...
Argalius Posted April 15, 2004 Share Posted April 15, 2004 Does anyone have a new problem yet? Link to comment Share on other sites More sharing options...
CodeOptimist Posted April 15, 2004 Author Share Posted April 15, 2004 Here's a simple problem:Solve these equations using substitution:2y - 3x = 2y + 2x = 5 Link to comment Share on other sites More sharing options...
Mystic-Al-Bob Posted April 16, 2004 Share Posted April 16, 2004 2y - 3x = 2 and 2y + 4x = 10 are given--> 2y - 3x - (2y + 4x) = 2 -10--> 7x = 8--> x = 8/7------------------------OR--------------------------------2y - 3x = 2 and y = 5 - 2x--> 2*(5-2x) - 3x = 2--> 10 - 7x = 2--> x = 8/7 Link to comment Share on other sites More sharing options...
MarkT Posted April 17, 2004 Share Posted April 17, 2004 Give a formula for the area of a regular (perfect) hexagon in terms of the length of one of the sides. Link to comment Share on other sites More sharing options...
Sam Posted April 17, 2004 Share Posted April 17, 2004 ooh ooh I know this oneSL2 / 4{tan(180/S)}S=sides and L=side lengths(assuming that they would be the same)Did I get it right? Link to comment Share on other sites More sharing options...
MarkT Posted April 17, 2004 Share Posted April 17, 2004 Not the question I actually asked, but yes, that's correct.(Fitting 6 into that formula gives (3/2).sqrt(3).L^2, for a hexagon) Link to comment Share on other sites More sharing options...
Jeru Posted April 17, 2004 Share Posted April 17, 2004 Btw, Bob, I was always taught that one needs to find both x and y. Link to comment Share on other sites More sharing options...
Mystic-Al-Bob Posted April 18, 2004 Share Posted April 18, 2004 that's right. but when I have x I can get y very easily (you know 2y-3x=2 and x=8/7)or have you meant that you thaught you need two different x's and y's? Link to comment Share on other sites More sharing options...
Mystic-Al-Bob Posted April 21, 2004 Share Posted April 21, 2004 new question:a^2 + b^2 = -103a - b = 0not sure whether it's possible to answer or whether there is only one possibility Link to comment Share on other sites More sharing options...
DarkAngelBGE Posted April 21, 2004 Share Posted April 21, 2004 a^2 + b^2 = -10LOL Good luck everybody finding the solution. :P Link to comment Share on other sites More sharing options...
Mystic-Al-Bob Posted April 21, 2004 Share Posted April 21, 2004 maybe there are some complex numbers in the solution?! Link to comment Share on other sites More sharing options...
Klaas Posted April 21, 2004 Share Posted April 21, 2004 I don't think that's possible Edit:Oh complex numbers...can't remember how to work with those anymore Link to comment Share on other sites More sharing options...
DarkAngelBGE Posted April 22, 2004 Share Posted April 22, 2004 AH yeah complex numbers. SHould have said that, Bob. I will try my hand this afternoon, gotta go to school now. Link to comment Share on other sites More sharing options...
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